The invention is weaving, and the invention relates more particularly to the weaving of medium or heavy weight industrial webbing.
Medium or heavy weight industrial webbing is widely used, for instance, for truckload restraint systems, container tie downs, and other relatively high strength applications. Such webbings are typically woven in a double or multiple weave construction having an upper layer of fabric and a lower layer of fabric. The two or more layers are, of course, joined by many binders and further preferably include an inner layer of stuffer yarns.
Typically, medium or heavy weight industrial webbing is woven from synthetic multifilament yarn. While polypropylene is used when high strength is not necessary, high strength applications typically use nylon (polyamid) or polyester. Both nylon and polyester yarns have very high tenacity. Nylon yarn, however, because of its superior elongation actually requires more work to break. Polyester, because it has less elongation is beneficial since its elongation under load is less.
Various attempts have been made to strengthen industrial webbing. The Hammersla U.S. Pat. No. 4,856,837 utilizes vinyl coated yarns at the selvage edges of cargo slings. Ogata U.S. Pat. No. 4,600,626 shows a seat belt webbing which utilizes a first weft thread having a low bending stiffness and a second weft thread having a high bending stiffness. The Pickering et al. U.S. Pat. No. 4,981,161 shows a seat belt webbing having a soft, round edge. A combination of a multifilament yarn and a monofilament yarn is used as the filling or weft yarn. The Johnson U.S. Pat. No. 4,052,095 shows a web sling laminated with chloroprene rubber. The sides of the web are also covered with an elastomer. The Taki sling belt, U.S. Pat. No. 4,209,044, utilizes a sheath of polyamide filament yarns, and the face side of the belt is thicker than the back side.
While various modifications have been made for particular applications, there is a need to improve the strength of medium or heavy weight industrial webbings without adding substantial cost to the webbing.